In the past, water has been a plentiful and inexpensive commodity; however, it is becoming increasingly scarce and more expensive. Accordingly, past sprinklers utilized techniques to approximate uniform coverage by overlapping circles and sectors of circles, rectangular shapes and more recently irregular shapes; however, the previous art until the present invention, has failed to address the shortcomings of the underlying approach in dispersing the water. Whether they are impact, rotary or oscillating sprinklers, all known sprinklers attempt to produce a more or less uniform linear cord of spray and to advance this linear cord in a straight or circular path generally perpendicular to this cord. Furthermore, to generate these uniform cords of spray, water streams are impinged upon objects or forced through small openings to generate small droplets and mist uniformly distributed along the length of the cord.
This method creates a wide range of droplets sizes ranging from large drops to a fine mist with the larger drops traveling the greatest distance and the smaller drops decelerating quickly and falling short as a result of their respective aerodynamics. Even recent sprinklers which claim to cover irregular shapes still use a uniform cord of water adjusted in length by changing the elevation angle (range) or lowering a shield in front of the stream thereby breaking the entire stream into mist. The mist is generally lost by drifting in winds and evaporating.
Furthermore, with these small droplets, it is necessary to thoroughly saturate the organic lawn material until water can agglomerate into large droplets which make their way down to the soil. All the while, the organic matter is maintained in a saturated condition over essentially the total area which further increases evaporation. Ultimately, most water left in surface vegetation is lost to evaporation instead of being taken in by the roots. Losses are further increased because particles of small aerodynamic diameters drift and are difficult to accurately direct to the lawn.
The second aspect of efficiency which the present invention resolves is precise pointing. It is this precision which is most obvious to the user and consequently represents his main advantage. Perhaps the most undesirable characteristic of a watering system is for water to strike a building, walk, street or other unwanted area. For irregular shaped lawns, to avoid striking unwanted areas the water source must be located at many locations. For buried systems this means many separate heads and consequently more cost. For portable systems, this means moving the sprinkler many times and consequently more wasted user time and more inconvenience.
As an example of control difficulties, a commercial embodiment of U.S. Pat. No. 4,637,549 utilizes the lowered screen to prevent excessive range by disintegrating large droplets. In addition to the increased evaporation as previously described, the stream is diverted into a 30 or 40 degree wide wedge which by the manufacturer's own admission makes tight control impossible. Other patents cite controlled coverage as their advantage; however, it is the failure of these devices to address the fundamental deficiencies of the control method which defeats these attempts.
It is precision in range and precision in azimuth which the present invention provides to overcome these problems. Precision is provided in azimuth by the radial, non-rotary, action of the present invention. By indexing azimuth in narrow bands of approximately 3 to 6 degrees, and using a "power nozzle" with a comparable angle of dispersion, the present invention produces sharp cuts in azimuth. And due to the discrete stationary azimuth positions, the device can go from minimum range to maximum range and, vice versa within one azimuth increment. By the use of variable range angle and/or variable water pressure, the present invention provides a maximum to minimum radius (or "turn down ratio") of 5:1 or greater. In actuality, by varying the water pressure to a bubble tight shut off in several embodiments of the invention, the device can completely eliminate water coverage to any desired azimuth positions.
A valve linked to the range setting within the present invention decreases pressure at close in ranges. This has the combined effect of eliminating the damaging water blasting of close-in vegetation, decreasing the total water applied to the proportionally smaller close in areas, and decreasing the range simultaneously. This produces tight radial control and uniform watering.
A further embodiment of the present invention is provided by the addition of a second site specific data base. This data base contains information regulating the minimum desired range. The combination of the maximum range and this minimum range at site specific azimuth angles and a tight shut-off valve provides a discontinuous, point watering, system. This point watering system waters discrete trees, shrubs, gardens and architectural landscapes. While existing drip watering and root watering systems provide this precision, they do it at extensive cost and extreme inflexibility to change the pattern of water distribution.
This apparatus and control system lends itself equally to above ground or buried, "pop-up" sprinkler systems. Within the latter version, the base is designed to be buried and a piston device is interstitially configured between the base and the azimuth rotor.
The embodiments of the present invention thereby provide a water powered, articulated, actuation and control system which aims a precision, power jet, consolidated water stream to all coordinates within a polar coordinate system.